It has been conventionally known that four factors (an OCT3/4 gene, an SOX2 gene, a KLF4 gene, and a c-MYC gene) as nuclear reprogramming substances are transfected into a somatic cell to produce iPS cells (induced pluripotent stem cells). However, among the four factors, for example, the c-MYC gene can be a risk of tumor formation and thus is desired not to be used. That is, it is required to consider the combination of nuclear reprogramming substances.
In the Patent Literature 1, three factors (an OCT3/4 gene, a SOX2 gene, and KLF4 gene) as nuclear reprogramming substances are brought into contact with a pulpal stem cell to produce iPS cells. In the Non-Patent Literature 1, four factors (an OCT3/4 gene, an SOX2 gene, a KLF4 gene, and a Glis1 gene) as nuclear reprogramming substances are transfected into a somatic cell to produce iPS cells.
Patent Literature 1: WO 2010/013359
Non-Patent Literature 1: Momoko Maekawa et al., Nature, vol. 474, 225-229